The invention relates to a video endoscope, comprising an endoscope part, which has proximally a central image signal conductor and at least one optical waveguide, and a light supplying part, which can be coupled to the endoscope part and which has distally a central image signal conductor connection and a light supply arranged coaxially around the image signal conductor connection in the coupling area, wherein endoscope part and light supplying part are rotatable with respect to one another.
A video endoscope of this type is known from German Patent DE 39 14 825 C1.
In the case of such video endoscopes having two components that can be coupled to one another, for ergonomic reasons one requirement demands that, in the course of coupling, the image conducting or image transmission system and the light guiding or light transmission system be coupled in one operation. The separate coupling of fibre-optic cable and camera at different interfaces is time-consuming and laborious. Moreover, two separate cables are necessary, which usually issue in different directions which requires more space and conceals more view in the field of the surgical operation.
Systems of a universal coupling in which light and image are coupled in one go have therefore been developed.
One such coupling system, as provided by the Applicant, is described in German Patent Application DE 197 15 510 A1, wherein projecting axially from the endoscope part there is a first pin, which contains the image conducting system, and a further pin containing the light guiding system extends parallel thereto.
These two pins are inserted into corresponding depressions in the camera part, thereby ensuring an exactly aligned orientation of image conducting system and light guiding system in conjunction with a simple coupling operation.
What is disadvantageous about this system is that light and image are coupled rigidly, i.e. non-rotatably.
In numerous endoscopes, particularly in rigid endoscopes, usually the viewing direction is not implemented exactly in the longitudinal axis of the shaft the so-called 0° viewing direction, but rather in a manner deviating therefrom, for example in a 30° viewing direction. If, then, this endoscope is rotated during a surgical procedure, the image also necessarily rotates, for example, an image which is visualized on a monitor by the camera and which the surgeon observes. If the surgeon has carried out a 180° rotation in the body with the endoscope, for example, the image that he views would be upside down. However, since this is not desirable, rather surgeons want to see the image in the upright position, so-called image erecting systems have been developed and gained acceptance.
In the case of the rigid coupling, as described in German Patent Application DE 197 15 510 A1, this requires complex image erecting systems, as described, for example, in U.S. Pat. No. 6,097,423.
In the case of the video endoscope in German Patent DE 39 14 825 C1, as described in the introduction, the two coupled parts, namely the endoscope part and the camera part that feeds the illumination light, are rotatable. In this case, the image conducting or image transmission system is arranged centrally both in the endoscope part and in the camera part and is coupled at an interface.
At said interface, the light guiding system of the endoscope part is embodied in such a way that a ring of optical waveguides is arranged circumferentially around the central image conducting/image transmission system. A corresponding ring having an identical diameter is provided in the illumination light/camera part, which ring lies opposite the ring of optical waveguides of the endoscope part at the interface.
The optical waveguides usually comprise numerous thin optical fibres that are laid in a manner such that they are as far as possible bundled in the endoscope. These optical waveguide fibres have to be spliced to form the ring at the coupling place. The same correspondingly holds true for the camera part.
Accordingly, only those endoscope parts in which the spliced ring of optical waveguides corresponds exactly to the diameter of the ring at the camera part can be coupled to the camera part, since otherwise no illumination light can be transmitted.
In the case of small endoscopes having relatively thin shafts, the optical waveguides would then have to be spliced into a relatively large ring of optical waveguides at the interface, as a result of which, particularly in the case of small-calibre endoscopes, there is no possibility for optimal adaptation since the coaxial light ring required becomes relatively thin in the case of thin-calibre endoscopes and high coupling losses occur.
There is a need, however, for standard couplings both for large-calibre and for small-calibre endoscopes which contain a rotatable coupling for image erection, which simply and reliably enable the coupling operation in one go and which additionally exhibit optical waveguide coupling with the lowest possible coupling losses.
It is an object of the present invention, therefore, to further develop a video endoscope of the type mentioned in the introduction to the effect that a coaxial coupling of light and image is possible, where coupling losses are intended to be kept as low as possible, and a mechanically simple rotatability is possible.